The styling of CTA buttons in notices is not displaying correctly on legacy themes

[xristos3490]

Describe the bug

After a recent update to the WC core that prevents legacy themes from displaying blocks-based CSS classes, like wp-element-button, to reduce the risk/footprint for existing stores.

The new C&C-inspired notices are only applied to stores that have the Cart and Checkout blocks installed, without checking for an active block theme. This causes a problem with the CTA buttons, which do not appear visually appealing when a merchant has C&C blocks installed in a legacy theme.

I’m thinking of three possible solutions here:

• Re-evaluate core change
• Only apply the new notices for block themes that use C&C blocks
• Adjust the CSS rule that controls the styling of the CTA buttons for the notices to not depend on the wp-element-button class.

To reproduce

Steps to reproduce the behavior:

1. Go to a store using a legacy theme (e.g., Storefront) and ensure you use at least WC 7.8-beta1
2. Enable C&C blocks in the checkout process
3. Go to any single product page and add it to the cart.
4. Check the CTA button in the success notice and see that it's not working as expected.

Expected behavior

The button should be appearing on the right side of the notice.

Screenshots

[ralucaStan]

@pmcpinto I've added this to the list of issues for Cycle 4